Conventionally, in a vehicle having a fuel injection system, the concentration of oxygen in the exhaust gas is detected, and the combustion in the engine is controlled based on the detection results.
Such is disclosed, for instance, in Japanese Patent Laid-open No. Hei 6-280634, wherein an oxygen concentration sensor is provided in each of the exhaust pipes that lead out from the lower side of the engine to the left and right sides of the vehicle body. The exhaust pipes disclosed in this publication extend rearward to connect to the muffler, which is disposed at a rear portion of the vehicle body, and the oxygen concentration sensor is disposed at an intermediate portion of the exhaust pipe extending to the muffler.
In the case of such a structure adapted for a saddle ride type all-terrain vehicle (hereinafter referred to as “ATV”), i.e., the structure in which the oxygen concentration sensor is provided at an intermediate portion of the exhaust pipe, the influences exerted on the exhaust pipe and the oxygen concentration sensor by mud and/or water on the road surface are great. In view of the characteristic of the ATV, that it often travels on off-road terrain, such factors must be taken into account.
Thus, the oxygen concentration sensor provided so as to project from the exhaust pipe disposed at a side portion of the vehicle body must be provided while taking into account the restrictions it will exert on the living-comfort properties (ride comfort) for the rider as well as the influences exerted thereon by external forces. It is therefore an object of the present invention to satisfy such demands.